Conventionally, in an electrical appliance and the like, an electricity supply or the sending and receiving of an electrical signal is carried out through a cord, a cable, and the like, and for the aforementioned connections, the electrical connecting appliance comprising a plug, a socket, a connector and the like, is used. In this kind of electrical connecting appliance, if the connection thereof is loosened because the cord, the cable, and the like are pulled and the like for some reason, the connection between terminals is disconnected, or a contact failure and the like occur so as to have a possibility to cause trouble.
Therefore, there exists a conventional technology for maintaining the connected state of such electrical connecting appliance. For example, there is well-known a lock structure of a cord retaining apparatus comprising a clamper and a holder mutually connected, and while the clamper comprises an elastic engaging piece provided on a side wall of a main body of the clamper, and including an engaging portion on a front side which becomes a connecting side relative to the holder, the holder comprises a corresponding engaging portion engaging with the engaging portion of the clamper. Also, the elastic engaging piece of the clamper is connected to a support piece extending from the side wall of the clamper main body so as to be integrally formed with the clamper main body, and also the support piece extends in a direction of inclining to the front side from the side wall of the clamper main body (see Patent Document 1).